Overview

What Is Atrial Fibrillation?

Atrial fibrillation (AF) is an irregular heartbeat caused by abnormal, irregular electrical signals in the heart. Normally, your heart’s electrical system sends signals from the top chambers of heart (atria) at regular intervals to control the rhythm of your heartbeat. If the signals become irregular, or arrhythmic, it may cause atrial fibrillation or other irregular heart rhythms.

An irregular heartbeat prevents the atria from contracting normally. Instead, the atria quiver, decreasing the amount of blood ejected from the heart with each heartbeat.

AF is a complex condition affecting about five million people in the United States. It is responsible for 15 to 20 percent of all strokes. It is more common in people who are 65 and older, more often affecting men than women. There is a 1 in 4 risk that you or a loved one will develop AF. The earlier AF is diagnosed and treated, the more successful we are in helping patients experience longer, more enjoyable lives.

Types of atrial fibrillation

• Atrial flutter (A-flutter): With atrial flutter, the atria contract consistently at a very rapid rate and the ventricles may beat either in a regular or irregular rhythm.
• Heart block (atrioventricular block or AV block): Conduction to the ventricles from the atria is slightly delayed (first-degree heart block), intermittently blocked (second-degree heart block), or completely blocked (third-degree heart block). This is considered a slow heartbeat arrhythmia.
• Paroxysmal supraventricular tachycardia (PSVT): These heartbeats are typically felt as very rapid heart palpitations or pounding in the chest and are seen with all age groups.
• Premature beats or contractions: Often described as a "skipped" beat when they occur, they are frequently harmless and do not require treatment. When they occur very often or repetitively, they can lead to a more serious rhythm disturbance.
• Sick sinus syndrome (SSS): This is a condition where there is a malfunction of the sinoatrial node, the heart's normal pacemaker. As a result, several abnormal rhythms can occur, both fast tachycardias and slow bradycardias. This arrhythmia is most commonly seen in the elderly.
• Sinus bradycardia: A sinus rhythm (regular rhythm) but with a resting heart rate that is less than 60 beats per minute. This is considered a slow heartbeat arrhythmia.
• Sinus tachycardia: A sinus rhythm (regular rhythm) but with a resting heart rate that is greater than 100 beats per minute. This is considered a fast heartbeat arrhythmia.
• Supraventricular tachycardia (SVT): A generic term that refers to any arrhythmia that begins above the ventricles in the atria. Examples of SVT are atrial fibrillation/atrial flutter and paroxysmal supraventricular tachycardia. These are considered fast heartbeat arrhythmias.
• Ventricular tachycardia (V-tach or VT): A potentially life-threatening arrhythmia where the heart rate may be 100 to 240 beats per minute. Depending on the duration and rate of the VT, the heart may be unable to pump adequate blood through the body. This is considered a fast heartbeat arrhythmia.
• Ventricular fibrillation (V-fib or VF): A life-threatening heart rhythm that originates in the ventricles or lower chambers of the heart. The ventricles "quiver" in a chaotic, purposeless fashion and are unable to pump adequate blood through the body. Defibrillation must be provided immediately. This is considered a fast heartbeat arrhythmia.